Adequate ventilation and drainage is essential for normal middle ear function. The Eustachian tube is purported to function in middle ear ventilation, drainage, and protection. Chronic Eustachian tube dysfunction has been implicated in the pathogenesis of many otologic disorders and is thought to be a principal cause of surgical failures. Patients with chronic middle ear disease have often been shown to have a mechanical narrowing of the Eustachian tube, usually at the isthmus (junction of the bony and cartilaginous portions), other causes for ET dysfunction are functional disorders of the cartilaginous part. Narrowing of the isthmus alone was demonstrated to be an insufficient cause of otitis media. Increasing evidence was found that allergic disease and reflux may be two of the most important contributors of tubal inflammation causing otitis media with effusion.
The tube is ordinarily closed in the resting position and dilates to the open position typically with swallows, yawns, and with other voluntary or involuntary efforts. Tubal opening typically lasts less than one-half second. Closure of the tube is maintained by a valve-like function of the opposing mucosal surfaces, submucosal tissue, fat, muscle, and cartilage. The valve measures approximately 5 mm in length and lies within the cartilaginous portion of the ET located about 10 mm distal into the tube from the nasopharyngeal orifice's posterior cushion or torus tubarius. The patulous ET has been defined as an abnormal patency that results in autophony
A common problem resulting from Eustachian tube dysfunction is Otitis Media with Effusion (OME) or the presence of fluid in the middle ear with no signs or symptoms of acute ear infection. Persistent middle ear fluid from OME results in decreased mobility of the tympanic membrane and serves as a barrier to sound conduction. OME may occur spontaneously because of poor Eustachian tube function or as a response following Acute Otitis Media. This usually occurs in infants and children aged 1-6 y due to anatomical difference and physiological changes of the Eustachian tube. At birth the tube is horizontal and 17 to 18 mm long. It grows to be at an incline of 45 degrees and reaches the length of 35 mm in adulthood. Due to its' relatively horizontal position in childhood and because it is shorter, infants are more likely to suffer from Eustachian tube dysfunction.
Most surgical procedures performed at this time involve bypassing the blocked Eustachian tube by implantation of a surgical prosthesis, usually in the tympanic membrane (ear drum), for ventilation of the middle ear cavity via the external ear canal. Tympanostomy tubes are recommended for initial surgery. Often, however, complications are encountered with such tubes. The main complications associated with tympanostomy tubes insertion are divided to early and late. Early complications: persistent otorrehea 10-26%, blockage of the tube 0-9%, early extrusion, hearing loss. Late complications: persistent perforation after tube extrusion 3%. Scarring of the tympanic membrane, atrophic membrane 21-28%, granuloma 5-40%, Tympanosclerosis 40-65%, cholesteatoma 1%.